Start from scratch:
Have you still got coolant in the system?
If not, do you appear to have a leak anywhere? You might need to top it up and run it (carefully - keeping an eye on the temp gauge) to see if there's a leak.
Is the temperature sender plug connected? It connects to the top of the thermostat housing, on the right-hand side of the engine near the top.
If you've got coolant and no leaks, and the plug is connected, have you got access to multiecuscan and a laptop? You'll be able to fire up the fans using that, even on the free version, to make sure they work.
If the fans work, you can also check for fault codes. Here's a few to get you started:
P0115 Engine Coolant Temperature Circuit Malfunction
P0116 Engine Coolant Temperature Circuit Range/Performance Problem
P0117 Engine Coolant Temperature Circuit Low Input
P0118 Engine Coolant Temperature Circuit High Input
P0119 Engine Coolant Temperature Circuit Intermittent
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control; ECT Excessive Time to Closed Loop Fuel Control
P0126 Insufficient Coolant Temperature for Stable Operation
P0128 Coolant Thermostat Malfunction
The thermostat is a weak point on the Alfas. Tends to run cooler than it should when its on the way out. I'm no expert on it, but as an engineer I would expect any half-decent designer to make a system that fails open - rather run cool than overheat! Having said that, these are Alfas we're talking about, so anything is possible - could be the thermostat has failed shut, I guess. Let the car cool completely, then start her up, and, once she's warming up, feel the water pipes (careful - don't burn yourself). If they're all warming up, the thermostat has opened, but if, once she's hot, one or more pipes are still cold, you've got a problem.
Hope this helps. Let us know how you get on.